We show the spectrally resolved line flux in Figure REF 
for one case in the Polar accretion geometry,
with \(\dot{M} =3\times 10^{-5}~M_{\mathrm {J}}\,\mathrm {yr}^{-1}\) , \(M_{\mathrm {p}}=10~M_{\mathrm {J}}\) , and \(R_{\mathrm {p}}=2.04~R_{\mathrm {J}}\) .
The flux is the one seen by an observer looking into the accretion cone (within \(\theta _\mathrm {max}=46{\mbox{°}}\)  of the pole; see Figure REF ) and at 150 pc,
similar to the distance of well-known young star-forming regions such as Taurus, Lupus, or \(\rho \)  Ophiucus–Upper Scorpius.
As throughout this work, no absorption by the interstellar medium (ISM) is included, to separate the two effectsFor
the PDS 70 planets (\(d=113\)  pc), [1]} derived a \(V\) -band extinction \(A_V\approx 0.05\)  mag, or \(A_R=0.04\)  mag (at the \(R\)  band, which is around H \(\alpha \) ) using [2]} with \(R_V=5\) ..
Due to the absorption by the accreting gas, the line-integrated flux drops by about 32 %,
corresponding to an extinctionNote that \(A\equiv 2.5\log _{10}(F_0/F)\) 
and \(\Delta \tau =\ln (F_0/F)=\ln (10)\times \log _{10}(F_0/F)\)  are nearly equal (\(\Delta \tau =0.92A\) ) since \(\ln (10)=2.30\approx 2.5\) .
\(A_R/\left(\mathrm {mag}\right)\approx \Delta \tau = 0.4\) . We now discuss the wavelength-dependent extinction.
